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Need help on measuring spur gear

I am attempting to measure a change gear from a Grizzly G9972Z 11 x 26 lathe in order to make two mating gears. These gears will be part of a reverse tumbler. What I believe I have determined from an existing spur gear is; 35 tooth, root diameter is 1.281” (32.54mm), outside diameter is 1.452” (36.88mm). Using my 10x magnifier lenses, the pressure angle looks very similar to the chart in machinery’s handbook showing 20 degrees.

Is this enough information to calculate the dimensions for a 36 tooth mating gear? How do I go about these calculations? I have studied the machinery’s handbook but still do not understand. I would like to make a single point tool for a fly cutter and use a spindexer in the mill to make these gears.
Thanks

Thanks John. If I understand correctly, the diametrical pitch then is 25.4. Using this link www.doov.com/cgi-bin/tgc_spurgear.cgi, I input the diametrical pitch as 25.4, number of teeth as 36 and the pressure angle as 20. The program return the other values needed to make the gear.